The present invention relates to an address setting method, a client apparatus, a server apparatus and a client-server system which are suitably applicable to for example a wireless 1394 network system. More particularly, the present invention relates to an address setting method or the like whereby an address can be added or changed to keep up with a variation in state of connection occurring in a radio-communication unit of typically a wireless 1394 network entirely by introduction of a DHCP (Dynamic Host Configuration Protocol) into the radio unit so that the number of bus-resets in the entire network can be reduced.
As a multimedia interface for linking the digital AV (Audio-Video) world to the PC (Personal Computer) world, a IEEE 1394 bus draws attention. The IEEE 1394 bus is a high-speed bus having a transmission speed of at least several hundreds of Mbps. The IEEE 1394 bus has both transmission functions, namely, an isochronous transfer function for transferring continuous data such as moving-picture information and an asynchronous transfer function for transferring burst data as in the ordinary data communication. In addition, a variety of industries such as the AV world, the PC world and the broadcasting world adopt the IEEE 1394 bus as media for transmitting digital information at homes. This is because the IEEE 1394 bus offers a user-friendly way of using. To be more specific, the IEEE 1394 bus provides media which not only have a high performance but also meet plug-and-play requirements, with which hot-plug-in is possible, of which connectors and cables are easy to handle with.
Along the trend observed in the industries as described above, research of a wireless 1394 system is under way. The wireless 1394 system is a radio version of the IEEE 1394 bus. Even in a wire-communication system, a bus-reset due to a change in connection state raises a problem of an interrupted isochronous communication and, hence, a deteriorating quality. However, migration to a radio-communication system which offers good mobility and a high degree of freedom will cause the state of network connection to change frequently. Thus, the number of bus-resets is expected to increase accordingly. As a result, a bigger problem is conceivably raised.
It is thus an object of the present invention to provide an address setting method or the like which is capable of reducing the number of bus-resets in the whole network.
An address setting method provided by the present invention is an address setting method adopted in a client-server system to assign a network address to a radio-communication terminal wherein: a client executes the steps of: creating a priority-order assignment table of servers in accordance with a control signal received from at least one of the servers; selecting a server as close to the top one of the priority-assignment table as possible as a connection server and outputting a request for a connection to the connection server; establishing a connection with the connection server based on the reception of the request by the connection server; and requesting a connectable server to increase and set the number of addresses in case a settable address of the connectable server does not exist in an address pool, and a server executes the steps of: establishing a connection with a client by setting a settable address for the client in response to the client""s request for the connection for which the settable address exists in a pool of addresses; and issuing a request for redistribution of addresses in the pool to all servers in response to a client""s request to increase and set the number of addresses to which an address available in any of the servers can be allocated.
In addition, the present invention also provides an address setting method to be adopted in a client-server system to assign a network address to a radio-communication terminal wherein: a client executes the steps of: creating a priority-order assignment table of servers in accordance with a control signal received from at least one of the servers; periodically transmitting current contents of the priority-order assignment table to a presently connected first server; and establishing a new connection with a second server upon reception of a notice of establishment of the new connection from the second server and informing the first server of an end of an existing connection with the first server, the servers execute the steps of: forming a judgment as to whether or not a second server having a higher priority than a first server exists upon reception of a priority-assignment table from a client by the first server; setting an address for the client and establishing a connection with the client by the second server if an available address exists in the second server; and issuing a request for redistribution of addresses in the pool to all servers in response to a client""s request to increase and set the number of addresses to which an address available in any of the servers can be allocated.
Furthermore, the present invention also provides a client apparatus to be employed in a client-server system for assigning a network address to a radio-communication terminal, the client apparatus comprising: a table creation means: for creating a priority-order assignment table of servers in accordance with a control signal received from at least one of the servers; a server selection means for selecting a server as close to the top one of the priority-assignment table as possible as a connection server and outputting a request for a connection to the connection server; a connection establishing means for establishing a connection with the connection server based on the reception of the request by the connection server; and an address redistribution means for requesting a connectable server to increase and set the number of addresses in case a settable address of the connectable server does not exist in an address pool.
Moreover, the present invention also provides a server apparatus to be employed in a client-server system for assigning a network address to a radio-communication terminal, the server apparatus comprising: a connection establishing means for establishing a connection with a client by setting a settable address for the client in response to the client""s request for the connection for which the settable address exists in a pool of addresses; and an address redistribution means for issuing a request for redistribution of addresses in the pool to all servers in response to a client""s request to increase and set the number of addresses to which an address available in any of the servers can be allocated.
On the top of that, the present invention also provides a client apparatus to be employed in a client-server system for assigning a network address to a radio-communication terminal, the client apparatus comprising: a table creation means for creating a priority-order assignment table of servers in accordance with a control signal received from at least one of the servers; a table transmission means for periodically transmitting current contents of the priority-order assignment table to a presently connected first server; and a connection establishing means for establishing a new connection with a second server upon reception of a notice of establishment of the new connection from the second server and informing the first server of an end of an existing connection with the first server.
In addition, the present invention also provides a server apparatus to be employed in a client-server system for assigning a network address to a radio-communication terminal, the server apparatus comprising: a priority judgment means for forming a judgment as to whether or not a second server having a higher priority than a first server exists upon reception of a priority-assignment table from a client by the first server; a connection establishing means for setting an address for the client and establishing a connection with the client by the second server if an available address exists in the second server; and an address redistribution means for issuing a request for redistribution of addresses in the pool to all servers in response to a client""s request to increase and set the number of addresses to which an address available in any of the servers can be allocated.
Moreover, the present invention also provides a client-server system for assigning a network address to a radio-communication terminal wherein: a client comprises: a table creation means for creating a priority-order assignment table of servers in accordance with a control signal received from at least one of the servers; a server selection means for selecting a server as close to the top one of the priority-assignment table as possible as a connection server and outputting a request for a connection to the connection server; a connection establishing means for establishing a connection with the connection server based on the reception of the request by the connection server; and an address redistribution means for requesting a connectable server to increase and set the number of addresses in case a settable address of the connectable server does not exist in an address pool, and a server comprises: a connection establishing means for establishing a connection with a client by setting a settable address for the client in response to the client""s request for the connection for which the settable address exists in a pool of addresses; and an address redistribution means for issuing a request for redistribution of addresses in the pool to all servers in response to a client""s request to increase and set the number of addresses to which an address available in any of the servers can be allocated.
Furthermore, the present invention also provides a client-server system for assigning a network address to a radio-communication terminal wherein: a client comprises: a table creation means for creating a priority-order assignment table of servers in accordance with a control signal received from at least one of the servers; a table transmission means for periodically transmitting current contents of the priority-order assignment table to a presently connected first server; and a connection establishing means for establishing a new connection with a second server upon reception of a notice of establishment of the new connection from the second server and informing the first server of an end of an existing connection with the first server; and servers each comprise: a priority judgment means for forming a judgment as to whether or not a second server having a higher priority than a first server exists upon reception of a priority-assignment table from a client by the first server; a connection establishing means for setting an address for the client and establishing a connection with the client by the second server if an available address exists in the second server; and an address redistribution means for issuing a request for redistribution of addresses in the pool to all servers in response to a client""s request to increase and set the number of addresses to which an address available in any of the servers can be allocated.
In the present invention, a DHCP is introduced into typically a radio-communication portion of the wireless 1394 network. The DHCP is a protocol adopted in a system comprising a DHCP server and a plurality of DHCP clients wherein a fixed number of IP addresses in a pool of the DHCP server are automatically assigned to the DHCP clients. By adopting the DHCP in a radio-communication portion of a leaf in a network, an address is set for a movement of a client in this portion in accordance with the DHCP. That is to say, a radio-communication portion of a network where the state of connection changes greatly and frequently is virtually detached from a high-level layer which forms a wire-communication portion of the network. In this way, the high-level layer is protected and, as a result, the number of bus-resets in the entire system can be reduced.
In addition, the number of pool addresses allocated to each DHCP server is changed adaptively to dynamic mobility distribution of clients in order to allow addresses to be effectively utilized and the number of bus-resets to be reduced.